Heretofore, zoom lenses are used in the cameras of the aforementioned fields. Among them, as a lens type having less variation in the angle of view during focusing and less variation in the F-number during zooming, a zoom lens which includes a first lens group having a positive refractive power and fixed during zooming, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power and fixed during zooming disposed in order from the object side, in which the first lens group is composed of three lens groups of a lens group having a negative refractive power and fixed during focusing, a lens group having a positive refractive power and moved during focusing, and a lens group having a positive refractive power and fixed during focusing, disposed in order from the object side is proposed (for example, refer to Japanese Unexamined Patent Publication No. 11(1999)-030749, Japanese Unexamined Patent Publication No. 2001-021804, and Japanese Unexamined Patent Publication No. 2001-116993).